Nebraska Shark Week is setting sail with Matt Joeckel, Nebraska's state geologist and a professor in natural resources and earth and atmospheric sciences, in a video about the ancient seas that once covered the Cornhusker State. Sediments from these seas — which today we see as sedimentary rocks — provide a foundation for Nebraska's geologic history. The seas were also home to an array of strange fishes and marine predators — including sharks, plesiosaurs and mosasaurs.

One of the sharks, ptychodus, reached lengths of 33 feet and patrolled the inland seas over Nebraska some 90 million to 70 million years ago. Unlike the sharp, cutting teeth of today's great white shark, ptychodus featured a massive, crushing plate of lumpy teeth used to consume large bivalves and crustaceans that thrived in the Western Interior Seaway.

Some 100 million years ago, nearly all of Nebraska was engulfed by the Western Interior Seaway. The sea, which was hundreds of meters deep, was home to a variety of marine creatures, including ancient sharks.